What are the characteristics of Hemolytic Uremic Syndrome (HUS) in adults?

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Last updated: March 19, 2025 • View editorial policy

From the Guidelines

Hemolytic Uremic Syndrome (HUS) in adults is characterized by microangiopathic hemolytic anemia, thrombocytian, and acute kidney injury, with early manifestations including hematologic and renal function abnormalities that can be detected through frequent monitoring of hemoglobin and platelet counts, electrolytes, and blood urea nitrogen and creatinine 1. To diagnose HUS, a peripheral blood smear should be examined for the presence of red blood cell fragmentation when HUS is suspected, as recommended by the 2017 Infectious Diseases Society of America clinical practice guidelines 1. Key characteristics of HUS in adults include:

  • Microangiopathic hemolytic anemia
  • Thrombocytopenia
  • Acute kidney injury
  • Hematologic and renal function abnormalities that precede renal injury
  • Red blood cell fragmentation on peripheral blood smear Frequent monitoring of laboratory tests is crucial to detect early manifestations of HUS, particularly in people with diagnosed E. coli O157 or another Shiga toxin–producing organism infection 1. The diagnosis and management of HUS in adults require a comprehensive approach, including supportive care and, in some cases, specific treatments such as complement inhibition with eculizumab for atypical HUS. It is essential to consider the underlying cause of HUS, such as Shiga toxin-producing E. coli, to guide treatment and management decisions 1. In clinical practice, the detection of hematologic and renal function abnormalities is critical for early diagnosis and treatment of HUS, and frequent monitoring of laboratory tests is necessary to prevent long-term complications and improve outcomes 1.

From the FDA Drug Label

In Study C10-004, the median patient age was 35 (range: 18 to 80 years) All patients enrolled in Study C10-004 were required to have ADAMTS13 activity level above 5%; observed range of values in the trial were 28%-116%. Fifty-one percent of patients had an identified complement regulatory factor mutation or auto-antibody. Table 17 summarizes the key baseline clinical and disease-related characteristics of patients enrolled in Study C10-004. Table 17: Baseline Characteristics of Patients Enrolled in Study C10-004 Parameter | Study C10-004(N=41) Time from aHUS diagnosis until start of study drug in months, median (range) | 0.79 (0.03 – 311) Time from current clinical TMA manifestation until first study dose in months, median (range) | 0.52 (0.03-19) Baseline platelet count (× 109/L), median (range) | 125 (16 – 332) Baseline LDH (U/L), median (range) | 375 (131 – 3318)

The characteristics of Hemolytic Uremic Syndrome (HUS) in adults, as observed in Study C10-004, include:

  • Median age: 35 years (range: 18 to 80 years)
  • ADAMTS13 activity level: above 5% (observed range: 28%-116%)
  • Complement regulatory factor mutation or auto-antibody: 51% of patients
  • Baseline platelet count: median 125 × 10^9/L (range: 16 – 332)
  • Baseline LDH: median 375 U/L (range: 131 – 3318)
  • Time from aHUS diagnosis to start of study drug: median 0.79 months (range: 0.03 – 311)
  • Time from current clinical TMA manifestation to first study dose: median 0.52 months (range: 0.03-19) 2

From the Research

Characteristics of Hemolytic Uremic Syndrome (HUS) in Adults

  • Hemolytic uremic syndrome (HUS) is related to a renal thrombotic microangiopathy, inducing hypertension and acute renal failure (ARF) 3
  • The pathogenesis of HUS involves an activation/lesion of microvascular endothelial cells, mainly in the renal vasculature, secondary to bacterial toxins, drugs, or autoantibodies 3
  • HUS is characterized by hemolytic anemia with schistocytes, thrombocytopenia without evidence of disseminated intravascular coagulation, and renal failure 3

Types of HUS

  • Typical HUS is associated with a prodromal diarrhea, with blood in the stools, related to pathogenic enterobacteria, most frequently E. Coli O157:H7 3
  • Atypical HUS is not associated with diarrhea, may be sporadic or familial, and can be related to an overactivation of the complement alternate pathway 3, 4
  • Atypical HUS can be caused by genetic mutations in complement and complement regulatory proteins, leading to uncontrolled complement activity 4

Clinical Manifestations

  • HUS can present with extra-renal manifestations, including vascular disease of the heart, brain, and skin, pulmonary hypertension and hemorrhage, and pregnancy complications 4
  • Atypical HUS has a prevalence of 2.21 to 9.4 per million people aged 20 years or younger, with children between the ages of 0 and 4 being most affected 4

Treatment and Management

  • Plasma infusions and plasma exchanges are effective in most cases to treat hemolysis and thrombocytopenia 3
  • Eculizumab, a monoclonal antibody that inhibits the activation of C5, has shown significant long-term improvements in renal function and interruption of plasma therapy in patients with atypical HUS 5, 6, 7
  • Multidisciplinary healthcare is necessary for timely management of HUS, including adequate screening to monitor for sequelae and specialized interventions for extra-renal manifestations 4

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.